a) tight enough so that it does not slip on startup It can also be a process that takes several months and proceeds systematically through all six steps, perhaps with external support from a consultant or experienced motor shop. A megohm test, also known as amegger test, is one of the most frequently performed tests for insulation strength, thanks to its simplicity, but its best to combine it with other motor insulation tests. When a split AC system using a capillary tube is overcharged: Three general areas of problems in air-conditioning systems include electrical problems, mechanical problems, and: The evaporator coil operating temperature for a system with a 20F split, 85F return air, and 71F supply air is: A high temperature differential (more than 2 degrees) between return air temperature at the grille and the return air temperature at the unit indicates: When an air-cooled split system operates at low ambient temperatures: C) Low ambient controls are necessary for safe operation. A carbon brush probe attachment allows you to measure shaft voltage while a motor is rotating. Potential relays measure the back ______ developed across the _______ winding to operate the relay. An open internal motor overload is distinguished by: Motors that sit on resilient rubber rings typically use which type of mounting? A ScopeMeter and power quality sensor can help troubleshoot problems in the drive. Impact: Accelerated wear on rotating components resulting in bearing failure. Fox and McDonald's Introduction to Fluid Mechanics, Alan T. McDonald, John C Leylegian, John W Mitchell, Philip J. Pritchard, Rajesh Bhaskaran, Robert W Fox. Open motor winding failures can be identified by: Motor starting components can be made up of: C) Internal centrifugal switches, relays, starting, and running capacitors, When checking the resistance of a dual voltage delta motor there should be ________ resistance readings, When checking the resistance of a dual voltage wye motor there should be ________ resistance readings, The most common types of single phase compressor motors are: 19) A) (SPC), (CS), (CSR), (SPSC). This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. Whats the lead time on a new motor? As a technician's rule of thumb, fan speed should not be adjusted more than ________ percent above or below manufacturer's specifications. Opens are indicated by infinite resistance or impedance reading. Open windings are also caused by shorted turns, phase-to-phase shorts, ground-to-frame shorts, faulty internal coil-to-coil connections, severe overloads, and physically damaged coils. It should concisely answer what, where, when, how and possibly why. Thermal Stress Failures. For this reason, it is important to check machine alignment more than just at the time of installationprecision alignment is a temporary condition that can change over time. In addition, misalignment may feed vibration into both the load and the motor drive shaft. 195.201.81.185 (a) 1-Methylcyclohexene or 3-methylcyclohexene (b) Isopropenylcyclopentane or allylcyclopentane (c) Bicyclo[4.2.0]oct-7-ene or Bicyclo[4.2.0]oct-3-ene (d) (Z)-Cyclononene or (E)-cyclononene (e) (Z)-Cyclooctadecene or (E)-cyclooctadecene. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. Angular soft footangular soft foot occurs when one of the mounting feet is not parallel or normal to the mounting surface. Once the underlying causes are identified and understood, implementing preventive maintenance procedures through diagnostics testing is the best way to help remedy electric motor winding failures. More than one choice may apply. Everyone is busy. (Here are7 ways to screw up vibration analysis.). Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. Including a winding that is shorted phase-to-phase or turn-to-turn, has a shorted coil, is grounded at the edge of the slot or in the slot, or has a shorted connection. When charging a capillary tube system that holds 100 oz., the charge must be: B) Within 5 percent, between 95 and 105 oz. One of the most common causes of electric motor failure is bearing issues, responsible for around 51 per cent of failures. Temperature plays a major role in motor failure. Unfavorable operating conditionswhether electrical, mechanical, or environmentalcan dramatically shorten the life of an electric motor. When is the induced draft blower energized on an induced-draft furnace that uses hot surface ignition? De-energized testing runs a motor through its paces while its turned off. A megohmmeter can detect: Connected tools and sensors offer all key stakeholders with access to the data they need. Located between the stator and rotor, bearings are used to keep the rotor centred and shrink the air gap. Some plants prefer to perform their own motor repairs. When thats not possiblewhen internal resources are stretched or a repair is too complex, for exampleits critical to choose your motor repair shop carefully. The sigma currents are created as a result of the signal frequency, voltage level, capacitance and inductance in conductors. Copyright 2016-2021 Duke Electric. Many professionals believe that a flexible coupling eliminates and compensates for misalignment, but a flexible coupling only protects the coupling from misalignment. Solid state start relays can be checked by: Which of the following is NOT a standard mounting dimension for an electric motor? Note:A one-percent voltage unbalance may result in a six- to ten-percent current unbalance. The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors. Nearly all air conditioning condenser fans are ________ motors. Arming maintenance engineers and technicians with the right knowledge, prioritizing workload and managing preventative maintenance to monitor equipment and troubleshoot intermittent, elusive problems can, in some cases, avoid failures due to normal system operating stresses and reduce overall downtime costs. Determine a balanced chemical equation for the formation of barium chloride. Read More Improve Predictive Maintenance With Thermal MonitoringContinue, 2023 Accelix - All Rights Reserved | Privacy policy, Moving toward smart maintenance with prescriptive analytics, As solar production rises, remote monitoring can improve efficiency. Some motor failures will require asking fewer than five whys. If you know the basics of electric motor function, including the names of the main parts of both AC and DC motors, youll get the most out of the rest of this guide. If its a mission critical motor and downtime is costing the company big, is a spare available while you wait for a repair or replacement? Things to look for during an inspection of your motor include: Signs of corrosion, dirt or debris on components, including fins, windings, contacts and relay, A burning smell that may indicate overheating, Signs of wear on the commutator and brush assembly, Anything unusual with the motor mount, stator, rotor and belts, Dirt buildup, inadequate lubrication and signs of wear on bearings, A bearing housing thats hot to the touch, Loose connections, including in the starter switch and fuses\. Pipe strain refers to the condition in which new stresses, strains, and forces, acting on the rest of the equipment and infrastructure transfer backward onto the motor and drive to induce a misalignment condition. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. If they can't, lubricate them. The suction pressure on a split AC system that is running with an excessive evaporator heat load: The manufacturer's data on a split AC system indicates that the normal temperature drop should be 15F at the current operating conditions. Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. Improper lubrication, inappropriate mechanical loads, heat, contamination and shaft currents are all the usual suspects when it comes to bearing problems. Start by completely disconnecting the spindle motor from all power sources. Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors. Plant owners, operators, and managers can benefit from both integrated data and maintenance management with a single system. Open windings are also caused by shorted turns, phase-tophase shorts, ground-to-frame shorts, faulty internal coil-tocoil connections, severe overloads, and physically damaged coils. Plant managers seeking to maintain motor uptime, engineers who rely on precise data to monitor asset health, and maintenance managers trying to stay a step ahead of motor failures can access data. Acid test kits and sight glasses help to identify a system contaminated by moisture and acid. near the wall? With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. b) the minimum tension required to keep the belt from slipping at its maximum torque How is the subcooling of an air-conditioning system affected by a low refrigerant charge? This additional energy is not used to turn the motor shaft but circulates in the windings and ultimately contributes to internal energy losses. In the case of an overloaded motor individual motor components including bearings, motor windings, and other components may be working fine, but the motor will continue to run hot. But, while predictive maintenance techniques, such as vibration analysis, are often used to . There are four key strategies that you can undertake to restore or prevent premature failures in motor drive and rotating component: https://help.fluke.com/hc/en-us/requests/new, Fluke virtual demos and product selectors, Fluke 438-II Power Quality and Motor Analyzer, Fluke 289 True-RMS Industrial Logging Multimeter, How to use criticality analysis to prioritize assets, Electric motor efficiency and reliability: New testing approach matches real world conditions, See how the 438-II Motor Analyzer is building an underwater fan club, 3 ways to improve motor health with vibration testing, Five key test points for understanding motor drive efficiency and performance, Fluke 1587 Insulation Multimeter helps keep 1950s motors and generators running into the 21st century, A motor braking manufacturing plant steps up to proactive maintenance, Angular misalignment: shaft centerlines intersect but are not parallel, Parallel misalignment: shaft centerlines are parallel but not concentric, Compound misalignment: a combination of parallel and angular misalignment. Sounds simple. Keep all of your organizations assets up and running without downtime. At the simplest level, all three phases of voltage should always have the same magnitude. EASA's Root Cause Failure Analysis manual covers root cause methodology and the specfic stresses that affect each component of an electric motor. Your IP: |, free online repair or replace decision-making tool. Bearing failure can be caused by several things: A heavier load than designed for Inadequate or incorrect lubrication Ineffective bearing sealing Shaft misalignment Incorrect fit Normal wear Induced shaft voltages b) will not run at full speed or strength Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. Stator winding failures are generally attributed to groundwall or turn insulation failures. We wrap it up by looking at the bigger picture, including how to perform a root cause failure analysis, If you know the basics of electric motor function, including the names of the main parts of both AC and DC motors, youll get the most out of the rest of this guide. An open winding will display several different symptoms, depending on the motor's internal connection. It raises the clavicle. Look for a clear, comprehensive, standardized reporting process, including rigorous visual and written documentation. To diagnose a problem, there are three steps within each category to help quickly and efficiently manage the repair workflow: Before returning the machine to service, perform a quick screening to ensure the repairs are completed. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. Weve hinted at the need to take a systematic, big-picture approach to your electric motors, but heres where we stop beating around the bush: if you want to prevent motor failure, put a total motor management program in place at your plant. If the motor is less than 1/8 HP, it is almost always replaced. and preventive maintenance (PM). Cloudflare Ray ID: 7a12d477b814c226 The combination of data integration, management, and mobile access gives maintenance and operations staff the ability to cross reference process automation information with maintenance activity and inventory records. Reserve an intensive root cause analysis for repeated, high-cost motor failures. This can lead to bearing destruction within a few months of motor operation. Thats why its so important to get to the root cause of a failure. A) Adding refrigerant increases the system subcooling. Will the shop do the work themselves, or will they outsource it? A) motors, When hopscotch troubleshooting, follow the schematic and move the meter lead on the control side of the circuit from one control to the next, checking the voltage in and out of the control. Our tools can also check the drives output and power distribution, uncovering energy losses and improving efficiency. Troubleshooting motor failure signs to look for, Storing motor in a location without adequate climate control, Corrosion of motor shaft, bearings and rotor, Leakage current from the armature windings (DC motors). There are two kinds of soft foot: In both cases, soft foot can be caused either by an irregularity in the machine mounting feet, or in the mounting foundation upon which the feet rest. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. Gives a bottom-line summary of the essential information in the report in approximately 100 words. An open winding falls into which general motor failure area? Always keep accurate and detailed records of your inspection and testing and keep them in one place to make it easy to identify trends and keep track of actions taken. Which NEMA classification that can withstand the highest temperature? The resistance of ________ can accurately be predicted using Ohm's law. EASA-validated. Soft foot refers to a condition in which the mounting feet of a motor or driven component are not even, or the mounting surface upon which the mounting feet sit is not even. Weve spent most of this guide talking about what to do when a motor fails. 13% of motor failures are caused by bearing failure, and more than 60% of the mechanical failures in a facility are caused by bearing wear, so learning how to troubleshoot this potential problem is important. Winding Failures. Then we identify the 5 common causes of industrial motor failure. Extent of failure. A root cause failure analysis can be relatively quick and informal. Motor failure doesnt have to be a fact of life if you take this guides five key messages to heart. d) can be detected by comparing the actual winding resistance to the motor manufacturer's data This is another biggie. But anyone in the biz knows that behind that question is a whole lot of hemming and hawing, made worse by pressure cooker environments and a lack of information. What is a common symptom of a severely restricted filter drier? Impact: Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and eventual bearing failure. But it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. Check the bearings to make sure they can spin freely. Does the shop have a significant amount of experience with your motor? Potential relays measure the back ________ developed across the ________ winding to operate the relay. We also frequently offer a companion 2-day Root Cause Failure Analysis seminar which includes this book as well as a CD-ROM containing a color version of the book. Ball bearings are used in smaller motors, while the big boys will have roller bearings. Impact: Imbalance creates excessive current flow in one or more phases that then increases operating temperaturesleading to insulation breakdown. PM has been shown to reduce downtime by as much as 50%. What is their internal quality management system and how do they make sure theyre following it? The stator is the stationary part of the motor. Use a multimeter or an ohmmeter to test the voltage of the electric motor. This report may come from your motor shop. In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. Sigma current can be found in the motor cabling and is the sum of the current of the three phases at any one point in time. c) 1/64th inch deflection per 1 inch span between drive shaft and driven shaft A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. It can also detect the presence of dirt or moisture. Most problems with single-phase motors involve the centrifugal switch, thermal switch, or capacitor(s). Any of these, if present in enough concentration on the windings, can lead to an early failure. The life of a three-phase stator winding can be shortened dramatically when the motor is exposed to unfavorable operating conditions electrical, mechanical or environmental. Identify causes you eliminated and why. d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. If they dont pass the test, keep shopping. Fluke Accelix presents at FM Ireland 2018! Its responsible for 51% of motor failures. Read More Fluke Accelix presents at FM Ireland 2018!Continue, How thermal imaging fosters a better understanding of assets, Read More Every infrared picture tells a storyContinue. If the failure was catastrophic, repair may not be a good idea. Motor control systems are being utilized in critical processes throughout manufacturing plants. It may also occur as a result of excessive starts or reversals. Instrument to measure and diagnose: Fluke 810 Vibration Tester. 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Moisture and acid which general motor failure shaft but circulates in the report in approximately words... Unfavorable operating conditionswhether electrical, mechanical, or environmentalcan dramatically shorten the of... The highest temperature destruction within a few months of motor operation we identify the common... Within a few months of motor operation spindle motor from all power sources and shaft currents created! Relays measure the back ______ developed across the _______ winding to operate the relay and frequency a. Maintenance techniques, such as vibration analysis. ) tools can also check the to! Owners, operators, and running capacitors ________ can accurately be predicted using 's! Get to the mounting feet is not a standard mounting dimension for an motor! Standardized reporting process, including when to call in a motor 5 common causes of industrial motor reporting... Roller bearings almost always replaced all three phases of voltage should always have same! Manufacturing plants ScopeMeter and power quality sensor can help troubleshoot problems in report... The relay dynamic testing to identify issues with temperature, balance and distortion starts reversals... Operate the relay bearing failure are the culprit in some rotor failures do when motor! Sight glasses help to identify issues with temperature, balance and distortion can freely! Across the ________ stability of the following is not a standard mounting for. Are indicated by infinite resistance or impedance reading percent above or below 's! One of the following is not used to keep the rotor centred and the. And rotor, bearings are used in smaller motors, while the big boys will have roller.. All three phases of voltage should always have the same magnitude decision-making, including maintenance and histories... Reserve an intensive root cause methodology and the motor running, you can dynamic! Five key messages to heart inappropriate mechanical loads, heat, contamination and shaft currents are as. By moisture and acid restricted filter drier what to do when a....